Most electronic systems include printed circuit boards with high density electronic interconnections. A printed circuit board (PCB) may include one or more circuit cores, substrates, or carriers. In one fabrication scheme for the printed circuit board electronic surface features (e.g., pads, electronic interconnects, etc.) are fabricated onto opposite sides of an individual circuit carrier to form a pair of circuit layers.
In some applications, printed circuit boards can require gold or other metallic plating on particular surface features (e.g., pads, electronic interconnects, edge connectors, surface mount pads, and the like). In such case, the conventional processes for gold plating can require that the gold plating be done before etching the final image. Such conventional processes can use a two layer plating of nickel/gold acting as an etch resist or mask to prevent the surface features under the nickel/gold from being etched. However, during the conventional etching process, the edges of the surface features are exposed to the etching solution, and lateral etching occurs while the undesired surface copper is being etched. This lateral etching creates an undesired condition called “overhang” around the surface features. FIG. 1 illustrates a conventional gold plating process for plating a surface feature that results in an overhang.